Saturday, February 06, 1999
"Careful observation of the patellar tracking is necessary to determine that the proper amount of lateral release is performed to enhance patellar tracking," said co-author Paul D. Maitino, DO, junior associate, Joint Implant Surgeons, Inc., Grant Medical Center, Columbus, Ohio.
"Overuse of lateral release is avoided due to the detrimental vascular effects and has been reported to result in fracture of the patella as well as other complications. The use of a tourniquet in total knee arthroplasty may affect the quadriceps tension, which could result in a 'false-reading' of patellar tracking if the tourniquet is inflated."
A total of 99 knees in 76 patients were evaluated for the need for a lateral retinacular release before and after deflation of the tourniquet. Lateral release was performed only after deflation of the tourniquet. There were 26 males and 50 females. All knees were implanted using the Maxim knee system. The need for lateral retinacular release was determined using the rule of "no-thumbs" with visual evaluation of the tracking of the patellar component.
The study found that a total of 18 (18 percent) of the knees needed a lateral retinacular release before tourniquet deflation. After deflation of the tourniquet, only seven (7 percent) actually required lateral retinacular release. This represents a 61 percent reduction in the knees that actually require a lateral retinacular release.
"Many times, the surgeon evaluates the patellar tracking with the tourniquet inflated, oblivious to the effect of the pressure on the quadriceps muscle," Dr. Maitino said. "A 61 percent reduction in lateral releases supports the hypothesis that the resulting pressure from the tourniquet has an effect on patellar tracking. Evaluation of the patellar tracking before deflation of the tourniquet could lead to an abnormally high lateral release rate. Based on the observations of this study, the authors recommend that patellar tracking should be evaluated after deflation of the tourniquet."
In addition to Dr. Maitino, co-authors of the study are Adolph V. Lombardi Jr., MD, associate, Joint Implant Surgeons, Inc.; clinical assistant professor, of the division of orthopaedic surgery and of biomedical engineering, Ohio State University; and director, clinical research and chairman, section of orthopaedics, Ohio Orthopaedic Institute; and Robert A. Fada, MD, associate, Joint Implant Surgeons, Inc.